Figure 73. — Reproduction of Hughes micro- 

 phone. iUSNM 315083-4) 



telephone patents of inventors like Elisha Gray and 

 Amos Dolbear =' (see fig. 68), but had hired Thomas 

 A. Edison to invent a new transmitter. As will be 

 seen below, the new American Speaking Telephone 

 Company ceased giving competition to the Bell 

 Company in 1880. 



Both the Bell Telephone Company and the West- 

 ern Union Telegraph Company found a commer- 

 cially practical transmitter in a device that modulated 

 the current from a battery by varying the resistance 

 of the circuit. The Bell Company obtained patent 

 rights on such a transmitter from Emile Berliner and 

 the Western Union Company from Edison. In the 

 meantime other companies had also been formed 

 to enter the telephone business and had applied for 



53 Amos Dolbear, The Telephone, Boston and New York, 

 1877; "Researches in Telephony," Proceedings oj the American 

 Academy of Arts and Sciences, 1878-1879, vol. 14, pp. 77-91. 



Figure 74. — Diagram of Blake telephone 

 transmitter. The platinum bead is at H and 

 the carbon block at /. Reprinted (with per- 

 mission) from F. Rhodes, Beginnings of Teleph- 

 ony, Harper and Brothers, New York, 1929, 

 p. 80. 



PAPER 29: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY! II 



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